Universität Stuttgart
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Item Open Access Tailored nanocomposites for 3D printed micro-optics(2020) Weber, Ksenia; Werdehausen, Daniel; König, Peter; Thiele, Simon; Schmid, Michael; Decker, Manuel; Oliveira, Peter William de; Herkommer, Alois; Giessen, HaraldItem Open Access Fast bidirectional vector wave propagation method showcased on targeted noise reduction in imaging fiber bundles using 3D-printed micro optics(2023) Wende, Marco; Drozella, Johannes; Herkommer, AloisItem Open Access Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools(2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, HaraldItem Open Access Phase errors in high line density CGH used for aspheric testing : beyond scalar approximation(2013) Peterhänsel, Sandy; Pruss, Christof; Osten, WolfgangOne common way to measure asphere and freeform surfaces is the interferometric Null test, where a computer generated hologram (CGH) is placed in the object path of the interferometer. If undetected phase errors are present in the CGH, the measurement will show systematic errors. Therefore the absolute phase of this element has to be known. This phase is often calculated using scalar diffraction theory. In this paper we discuss the limitations of this theory for the prediction of the absolute phase generated by different implementations of CGH. Furthermore, for regions where scalar approximation is no longer valid, rigorous simulations are performed to identify phase sensitive structure parameters and evaluate fabrication tolerances for typical gratings.Item Open Access 3D printing of colored micro-optics(2023) Aslani, Valese; Toulouse, Andrea; Schmid, Michael; Giessen, Harald; Haist, Tobias; Herkommer, AloisItem Open Access Stitching-free 3D printing of millimeter-sized highly transparent spherical and aspherical optical components(2020) Ristok, Simon; Thiele, Simon; Toulouse, Andrea; Herkommer, Alois; Giessen, HaraldItem Open Access 3D direct laser writing of highly absorptive photoresist for miniature optical apertures(2022) Schmid, Michael D.; Toulouse, Andrea; Thiele, Simon; Mangold, Simon; Herkommer, Alois; Giessen, HaraldThe importance of 3D direct laser writing as an enabling technology increased rapidly in recent years. Complex micro-optics and optical devices with various functionalities are now feasible. Different possibilities to increase the optical performance are demonstrated, for example, multi-lens objectives, a combination of different photoresists, or diffractive optical elements. It is still challenging to create fitting apertures for these micro optics. In this work, a novel and simple way to create 3D-printed opaque structures with a highly absorptive photoresist is introduced, which can be used to fabricate microscopic apertures increasing the contrast of 3D-printed micro optics and enabling new optical designs. Both hybrid printing by combining clear and opaque resists, as well as printing transparent optical elements and their surrounding opaque apertures solely from a single black resist by using different printing thicknesses are demonstrated.Item Open Access Opposed-view dark-field digital holographic microscopy(2014) Faridian, Ahmad; Pedrini, Giancarlo; Osten, WolfgangScattering and absorption belong to the major problems in imaging the internal layers of a biological specimen. Due to the structural inhomogeneity of the specimen, the distribution of the structures in the upper layers of a given internal structure of interest is different from the lower layers that may result in different interception of scattered light, falling into the angular aperture of the microscope objective, from the object in each imaging view. Therefore, different spatial frequencies of the scattered light can be acquired from different (top and bottom) views. We have arranged an opposed-view dark-field digital holographic microscope (DHM) to collect the scattered light concurrently from both views with the aim to increase the contrast of internal structures and improve the signal-to-noise ratio. Implementing a DHM system gives the possibility to implement digital refocusing process and obtain multilayer images from each side without a depth scan of the object. The method is explained and the results are presented exemplary for a Drosophila embryo.Item Open Access Distortion-free multi-element Hypergon wide-angle micro-objective by femtosecond 3D printing(2020) Weber, Ksenia; Wang, Zhen; Thiele, Simon; Herkommer, Alois; Giessen, HaraldItem Open Access 3D printed stacked diffractive microlenses(2019) Thiele, Simon; Pruss, Christof; Herkommer, Alois; Giessen, Harald